Have unittests import mock from ansible.compat so they work on py3 without mock installed from pypi

test/units/module_utils/test_database.py

@@ -1,5 +1,4 @@
 import collections
-import mock
 import os
 import re
 
@@ -24,6 +23,8 @@ except ImportError:
             else: excName = str(expected)
             raise AssertionError("%s not raised" % excName)
 
+from ansible.compat.tests import mock
+
 from ansible.module_utils.database import (
     pg_quote_identifier,
     SQLParseError,